Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine (1914)

Page scan 00090 from Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine

Record Details:

Title:
Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine
Date:
1914
Author:
Gage, Simon Henry, 1851-1944
Publisher:
Ithaca, N.Y. : Comstock Publishing Company
Volume:
Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine
Leaf #:
00090
Language:
English
Subjects:
Lantern projection, Motion picture projection
Format:
Books
Contributor:
University of California Libraries
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
Bibliography: p. 693-703
Date Added:
July 19, 2022
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CH. II] MAGIC LANTERN WITH ALTERNATING CURRENT 75 must see to it that the carbons are brought toward each other occasionally by turning the proper screws. With moderate currents the lamp will run from five to ten minutes without feeding, but the greater the amount of current the oftener must the carbons be fed together. As stated above, the noise increases with the length of the arc ; therefore the carbons should be brought nearer together every two to four minutes. § 118. Shadows on the screen. — All the defects indicated under "troubles" in chapter i (§83) for the direct current light are liable to appear when using alternating current. This is somewhat complicated by the presence of an equally brilliant crater on both the upper and the lower carbons. As with direct current, there is less trouble with right-angled carbons than with vertical or inclined ones. With right-angled carbons the defect is greatest when the lower carbon is too high, thus shading the upper carbon, as in fig. 25 A (for the shadows see fig. 24—25, 27-29). As with the direct current, the greater the aperture of the projection objective, the less marked is the screen defect of a slight mal-position of the carbons. (See also Ch. Ill, § 127, Ch. IX, § 417, and Ch. X, § 488 for the arc lamp with small carbons to be used on the house lighting system).